A fully functioned computer, besides including a CPU, memory and logic chip sets on a mainboard, also has to include peripheral devices that are coupled with the mainboard through various I/O interfaces to expand the function of the computer.
In large computer equipment such as the hosts of network servers or industrial servers, in addition to providing more powerful performance than the PCs, the peripheral devices also have to be equiped with enhanced performance to catch up with the server to meet the requirement of high loading. Hence the expansion cards installed on a large computer often are longer than the ones used on the PCs to contain more and larger chip sets, to process high loading and complex operations. The expansion cards used on the servers almost have the same length as the case of the servers. The expansion cards usually adopt PCI and ISA slots as connection interfaces. These expansion slots have limited coupling strength. Hence the expansion cards are prone to becoming disengaged from the expansion slots during assembly or transportation, and could cause defective contact and result in malfunction of the servers.
To prevent the expansion cards from becoming disengaged from the expansion slots, the conventional approach is to set various retention devices on the chassis. FIG. 1 illustrates a conventional expansion card retention device. There is a frame 1 located in a server chassis to form a card receiving area. The frame 1 includes a circuit board 2 and a plurality of expansion slots 3 on the bottom. A latch member 4 with a substantially L-shaped cross section is provided that has a hinge 4a and a latch section 4b. The hinge 4a is pivotally coupled on a front wall of the frame 1 and may be swiveled close to the front side wall to move the latch section 4b to the upper edge of the front wall of the frame 1, and to extend the front edge of the latch section 4b towards the interior of the frame 1. After a plurality of expansion cards 5 are engaged in the expansion slots 3, the latch member 4 is swiveled to couple the latch section 4b on the upper edges of the distal ends of the expansion cards 5. The expansion cards S may be latched securely without becoming disengaged from the expansion slots.
The aforesaid retention device aims to couple a plurality of expansion cards 5. If the expansion cards 5 have different heights, they receive different pressure and the retention effect varies. When changing and replacing a single expansion card 5, the rest of the expansion cards 5 also have to be unlatched. It is not possible to change and latch the expansion cards 5 individually. Hence all expansion cards have to be inspected and tested anew after every change operation. Moreover, the latch member 4 is swiveled about an axis parallel with the front wall and moved close to the front wall, or moved away from the front wall. Such a coupling relationship has to reserve a sufficient operation space outside the front wall of the frame 1 to enable the latch member 4 to be swiveled as desired so that the expansion cards 5 may be latched or removed. Such a device does not efficiently utilize the interior space of the chassis.